HIGH-PRECISION RADIOTHERAPY FOR 30 LOW-GRADE GLIOMAS - FIRST RESULTS WITH EMPHASIS ON LATE DELAYED RADIATION-INJURY DEPICTED ON MAGNETIC-RESONANCE TOMOGRAPHY

Between 11/89 and 7/92 thirty patients with low grade glioma were trea ted at the German Cancer Research Center by 3-dimensional planned high precision radiotherapy. Magnetic resonance tomography (MRT) is extrem ely sensitive to detect late delayed brain injury following irradiatio n. Thus, all patients had MR scans taken before and after irradiation. The median follow-up time is 24.2 months. Diffuse or focal white matt er disease depicted on MR outside the 80% isodosis of the irradiated t umor was not observed. Further. average irradiation doses using integr al of dose-volume histograms were calculated for different organs at r isk, e.g. brain stem. In none of the patients the tolerance dose 5/5 o f the evaluated organ at risk was reached. It is concluded that high p recision radiotherapy is effective in reducing adverse effects of radi otherapy using signal intensity on T2 weighted MR images as an indicat or of brain damage.